A dactyl (/ˈdæktɪl/; Greek: δάκτυλος, dáktylos, “finger”) is a foot in poetic meter. In quantitative verse, often used in Greek or Latin, a dactyl is a long syllable followed by two short syllables, as determined by syllable weight. In accentual verse, often used in English, it is a stressed syllable followed by two unstressed syllables—the opposite is the anapaest (two unstressed followed by a stressed syllable).

The Greek and Latin words δάκτυλος and dactylus are themselves dactyls (and hence autological). The English word poetry is also a dactyl. A useful mnemonic for remembering this long-short-short pattern is to consider the relative lengths of the three bones of a human finger: beginning at the knuckle, it is one long bone followed by two shorter ones (hence the name dactyl).

A dactyl is like a finger, having one long syllable followed by two short syllables.

Another example: the opening lines of Whitman's "Out of the Cradle Endlessly Rocking" (1859), his poem about the birth of his poetic voice:

Out of the cradle, endlessly rocking [a dactyl, followed by a trochee ('cradle'); then another dactyl followed by a trochee ('rocking')]

Out of the mockingbird's throat, the musical shuttle [2 dactyls, then a trochee ('throat, the'); then another dactyl, followed by a trochee]

. . .

The dactyl "out of the..." becomes a pulse that rides through the entire poem, often generating the beginning of each new line, even though the poem as a whole, as is typical for Whitman, is extremely varied and "free" in its use of metrical feet.

Dactyls are the metrical foot of Greek and Latin elegiac poetry, which followed a line of dactylic hexameter with dactylic pentameter.

In Joyce's Ulysses opening chapter Buck Mulligan quips that his own name is a dactyl. Mull-i-gan.